Problem
Non-destructive ToFD inspection showed several 6 inch high pressure boiler water lines in a refinery experiencing potential cracking in the circumferential welds which required a repair to continue operations.
Conditions
With the presence of 4mm or less remaining wall and/or type of indication i.e. cracking on several sections of the boiler lines, a repair was urgently required in order to sufficiently reinforce the thinned area to prevent failure due to propagation of the cracks. The design specifications of the repair required was a pressure of 8100kpa and temperature of 130 Degrees Celsius. Due to location of the pipework, all work was completed on a specially built scaffold with limited working space.
Solution
Due to the condition of the line, surface preparation was limited to pneumatic power tools to SSPC SP11 fear of rupturing the line with the aggressive surface preparation methods. An engineered high temperature carbon fiber composite repair system which was developed for the repair of high risk pipeworks was used for the repair. This high strength composite material utilizes a specialized epoxy system that provides excellent physical properties even in high temperatures conditions while also giving a long working time for the installation on large diameter pipe in hot environments.
The repair was engineered to prevent an eventual full circumferential slot defect of 2.5mm. The engineered carbon fiber composite wrap was then applied circumstantially at the calculated number of layers over all areas of concern, thus fully restoring the integrity of the pipe for continued safe operation.
Result
In just a day, a total of 4 section of the pipework with the potential of failure were repaired and reinforce to prevent a catastrophic failure. This preventive maintenance program allowed safe operations of the plant without costly unscheduled shutdown till the next available turnaround.
